Process of preserving wood



Patented June 30, 1953 ED STATES No Drawing. Application August 7, 1951, Serial N 0. 240,776

9 Claims. (Cl. 117-57) (Granted. under Title ggP. S. Code (19-52),

sec. 1

The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes throughout the world without the payment to me of any royalty thereon.

I hereby dedicate the invention herein described to the free use of the people in the territory of the United States to take effect on the granting of a patent to me.

This invention relates to preserving and pulping of wood.

In general, according to the invention, the mold Trz'choderma viride is cultured on green wood (recently cut wood) which is to be used for pulp or for posts, poles, ties, or other Wood products, the green wood having had an inorganic fluoride, such as sodium fluoride, ammonium fluoride, ammonium bifiuoride, and cupric, magnesium, sodium, and zinc silicofluorides, applied on the surface thereof, as by dipping or spraying. This mold treatment reatly increases the permeability of the wood. The resulting wood is then impregnated with a liquid wood preservative, such as light and heavy preservative oils like pentachlorophenol in kerosene or in heavy petroleum carriers, or coal-tar creosote and water-carried preservatives such as sodium pentachlorophenate, boraX, zinc chloride, and so forth. Also the fluoride-Trichoderma treated wood described above is pulped with conventional pulping liquors, such as sulfate and sulfite liquors in accordance with conventional pulping procedures.

The effect of this combined fiuoride-Trichoderma treatment directly inhibits the growth of decay fungi during seasoning and storage of the wood.

In culturing the Trichoderma m'rz'cle on the fluoride treated wood, it is essential that the fluorides shall not have been used in excessive amount, otherwise the growth of the mold will be inhibited. I Spray or dip treatments using from 2 to 4% sodium fluoride or from 2 to 5% ammonium bifiuoride solutions are effective to promote the desired luxuriant growth of the mold.

In carrying out the invention, posts and pulpwood that had become heavily molded with 'I'richoderma following sprays with fluoride solutions absorbed and retained from 8 to 20 pounds of both light and heavy preservative oil solutions during a cold immersion treatment, whereas matched specimens of unmolded wood from the same trees absorbed only 1 to 2 pounds per cubic foot. Penetration of the solutions in endcoated pieces of 3 to 5 inches in diameter often was complete for the molded wood, in contrast to shallow sidepenetration of .1 to .25 inch for the unmolded wood. Similar differences in favor of the molded wood were obtained with gum, although total absorption and penetration usually were somewhat less than with pine.

Comparative tests with water alone and a water-carried preservative solution containing a 4% mixture of sodium pentachlorophenate, sodium bicarbonate and borax were also carried out. Absorptions for the molded wood ranged from 3.5 to 8 pounds of solution per cubic foot as compared to less than 1 pound usually for unmolded wood. Thus, the penetration of watercarried salt as well as oil preservatives wasgreatly facilitated by the fluoride-Trichoderma process.

While the increased permeability of Trichoderina molded wood has been described above as particularly applicable to the wood preservation field, wider adaptations of the process are comprehended in the seasoning and pulping of wood.

Thus, if wood of low permeability is seasoned rapency considerably. In the pulping field, the penetration and movement of the cooking chemicals durin conventional pulping of wood chips are important factors in the speedof the pulping operation, consumption of chemicals, and quality of the pulp produced. This is especially true in conventional sulfite pulping but also applies to a large extent to conventional sulfate pulping. With perfect penetration and distribution of the chemicals, as would be realized with completely permeable wood, the chips can be raised to the pulping temperature immediately and pulping action will be uniform throughout the chips. Increasing permeability of the wood, according to the present invention, results in an overall saving of time in the pulping process and also in greatly improving the average quality of the pulp. Furthermore, the production of screening rejects which result from non-uniform pulping of wood of low permeability'is reduced.

Having thus described my invention, I claim:

1. A process of preserving wood comprising culturing Tric'hoderma m'rz'de on green wood which has had an inorganic fluoride applied to the surface thereof, whereby the permeability of the wood is increased, and impregnating the resulting wood with a liquid wood preservative.

'2. The process of claim 1 wherein the fluoride is sodium fluoride.

3. The process of claim 1 wherein the fluoride is ammonium bifiuoride.

i. The process of claim 1 wherein the fluoride is a silico-fluoride selected from group consisting of cupric, magnesium, sodium, and zinc silicofiuorides.

5. The process of claim 1 wherein the wood preservative is a preservative oil.

6. The process of claim 1 wherein the wood preservative is water-carried borax.

7. The process of claim 1 wherein the wood preservative is water-carried sodium pentachlorophenate. V p

8. The process of claim 1 wherein the wood preservative is water-carried zinc chloride.

9. The process of claim 1 wherein the wood preservative is water-carried copper sulphate.

RALPH M. LINDGREN.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date 119,224 Eaton Sept. 26, 1871 260,749 Ekman July 11, 1882 575,973 McLachlan Jan. 26, 1897 5 1,248,711 Teesdale Dec. 4, 1917 1,521,977 Tolmer Jan. 6, 1925 2,029,973 Wells Feb. 4, 1936 2,045,350 Grifiin June 23, 1936 2,128,928 Estes Sept. 6, 1938 10 2,240,017 Primavasi Apr. 29, 1941 2,296,316 Stamm Sept. 22, 1942 2,491,015 Poole Dec. 13, 1949 FOREIGN PATENTS Number Country Date 28,729 Great Britain 1904 OTHER REFERENCES Chidester et al.: Technical Assn. Papers, Series 21, pages 137-140 (1938). 

1. A PROCESS OF PRESERVING WOOD COMPRISING CULTURING TRICHODERMA VIRIDE ON GREEN WOOD WHICH HAS HAD AN INORGANIC FLUORIDE APPLIED TO THE SURFACE THEREOF, WHEREBY THE PERMEABILITY OF THE WOOD IS INCREASED, AND IMPREGNATING THE RESULTING WOOD WITH A LIQUID WOOD PRESERVATIVE. 